Immune System + Cancer - TOKA

Question 1

What is cancer?

Answer 1

Imbalances in rate of cell division and cell death

Ex: Tumors happen when cells divide more rapidly than they die

Question 2

What can cause transformation of cells, resulting in tumors?

Answer 2

1. Carcinogens
2. Radiation
3. Viral infections
4. Chronic inflamm.
5. Genetic mutations

Question 3

What are tumor-specific antigens?

Answer 3

Ag found on tumor cells but NOT on normal host cells

*** easier for IR to react and eliminate

Question 4

What are tumor-associated antigens?

Answer 4

Ag expressed on tumor cells AND normal host cells

**makes it hard for Immune system to fight off

Question 5

How do neutrophils respond to tumors?

Answer 5

by producing TNF-related apoptosis-inducing ligand

** stimulates apoptosis of tumor cells

Question 6

How do NK cells help respond to tumors?

Answer 6

expresses NKG2D (activating receptor on NK cells) which binds to MICA and MICB stress molecules on tumor cells

*** leading to killing of tumor cell

Question 7

Which macrophage type helps to kill tumor cells: M1 or M2?

Answer 7

Classically activated M1 helps kill many tumor cells

Question 8

How do M2 macrophages play a role in tumors?

Answer 8

PROMOTES tumor growth (bad!!) by secreting

VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF) + TGF-b

Question 9

How do M1 macrophages kill tumor cells?

Answer 9

Through production of nitric oxide (NO)

Question 10

How are macrophages activated to kill tumor cells?

Answer 10

Tumor-specific CD4+ T cells produce INF-y which activates M1 macrophages

Question 11

How do CD8+ T cells help eliminate tumor cells?

Answer 11

Directly lyses tumor cells using perforins and granzymes

Question 12

How do CD4+ T cells help eliminate tumor cells?

Answer 12

produces IFN-y to activate macrophages to kill tumor cells

Question 13

How do NKT cells play a role in eliminating tumor cells?

Answer 13

NKT cells can recognize Ag presented on a non-classical MHC 1 molecule on tumor cells

Question 14

How do antibodies help eliminate tumors?

Answer 14

Mediates killing by activating complement or by ADCC

(Ab binds to complement to start classical pathway)

Question 15

How do tumor cells suppress/escape host immune responses?

Answer 15

Makes TGF-b which suppresses IR and induces PROLIFERATION + ANGIOGENESIS of tumor cells

** angiogenesis bc blood vessels feed the tumor + allow it to survive

-Tumor-activated DC secrete indoleamine (IDO) - suppresses T cells

• Secretes galectin-1 - stimulates angiogenesis
• Secretes PDL1 which suppresses T cell IR

Question 16

Explain what tumor equilibrium is?

Answer 16

When the tumor cell is there but does not progress/proliferate

Question 17

What are some approaches to tumor immunotherapy?

Answer 17

1. Non specific Immune Stimulation
   (Ex: BCG - releases pro inflamm cytokines to help IR)
2. Passive immunization
   (Ex: monoclonal Ab against tumor Ag)
3. Active immunization

Question 18

What is adoptive transfer?

Answer 18

When lymphocytes are removed from patient, inoculated with IL-2, then activated lymphocytes are injected back into the patient bearing the tumor

Question 19

Tumor cells express PD-L1 which binds to PD-1 on CD8+ T cells to suppress their function. How can this be avoided?

Answer 19

Admin of Anti-PD-1 Ab

binds to PD-1 on CD8+ T cells to block tumor cell from binding PD-L1